BLZ File

What are BLZ files and how to open them

Are you having problems opening a BLZ file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your BLZ files.

What is a BLZ file?

A .BLZ file is a BriefLZ Compressed Data file.

The BriefLZ Compressed Data format stores data that has been compressed using the BriefLZ library from Ibsen Software. It is used when one needs fast lossless compression of arbitrary binary data using a small memory footprint and simple algorithms. Compressed data in this format can be stored or transmitted and then restored to the original data by decompression.

Files in this format are created by programs that use Ibsen Software's BriefLZ library (often via the utility blzpack or linked library functions). The original data is divided into literal bytes and backward-reference matches (length, offset pairs) using a variant of Lempel-Ziv type compression. The compressed output is a compact sequence encoding uncompressed runs and repeated sequences. Decompression routines provided in the library read the compressed stream, rebuild the matches and literals, and restore the exact original data.

Files in this format begin with a four-byte magic number 62 6C 7A 1A (ASCII "blz" plus 0x1A) at offset zero for identification. Versions of the library support packing with different compression levels; functions like blz_pack, blz_pack_level, blz_depack, and blz_depack_safe are defined in the header brieflz.h.

How to open BLZ files

Important: Different programs may use files with the BLZ file extension for different purposes, so unless you are sure which format your BLZ file is, you may need to try a few different programs.

While we have not verified the apps ourselves yet, our users have suggested three different BLZ openers which you will find listed below.

Last updated: August 24, 2026

Various apps that use files with this extension

These apps are known to open certain types of BLZ files. Remember, different programs may use BLZ files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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